1. Field of Invention
The present disclosure relates to a permanent motor. More particularly, the present disclosure relates to an inductance measuring device and a method for measuring an inductance parameter of the permanent motor.
2. Description of Related Art
Currently, during measuring of an inductance parameter of an AC motor, a current measuring method measures the inductance parameter when the motor is in a stationary state by inputting different voltage or current and locking the motor using a mechanical contracting brake device. However, after the mechanical contracting brake device is incorporated, commonly more measuring space is occupied and the measuring cost is increased, such that the measuring efficiency of the inductance parameter is poor.
Furthermore, another current measuring method obtains a phase inductance through experiments and then indirectly obtains a d-axis inductance and a q-axis inductance through a complex calculation and deduction process. In a common inductance measuring method such as the Dalton inductance measuring method, the measuring circuit is connected to each of three phases A, B, C, and a two-by-two connection (AB, BC or CA) is implemented, such that an alternative current (AC) close to a rated current is inputted into the circuit, and terminal voltage and current corresponding to the circuit with the two-by-two connection are recorded, so as to obtain a three-phase inductance. At this time, the AC is only inputted into arbitrary two of the three phases and the phase left is not energized, such that no magnetic linkage is generated in the two energized phases, thereby naturally forming no mutual inductance between the two phases. In this measuring method, a d-axis inductance and a q-axis inductance can be solved by using the three-phase inductance. However, in this measuring method, in the process of indirectly obtaining each d-axis inductance and each q-axis inductance, the calculation is extremely complex and the error is great, which brings much inconvenience in an actual measuring application.
In view of this, many in the industry are endeavoring to find ways in which to design a novel inductance parameter measuring device and method when the permanent motor is in a stationary state, which does not need any additional auxiliary device such as the mechanical contracting brake device and can provide a simple calculation method which is easy to be operated.